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Abstract:

Exemplary embodiments are directed to variable power wireless power
transmission. A method may include conveying wireless power to a device
at a first power level during a time period. The method may further
include conveying wireless power to one or more other devices at a
second, different power level during another time period.

Claims:

1. A wireless charging device, comprising:at least one transmitter having
an associated transmit antenna;wherein the at least one transmitter is
configured to operate in a first power mode while a first device is
positioned within an associated charging region, and a second reduced
power mode while one or more other devices are positioned within the
charging region.

2. The device of claim 1, wherein the at least one transmitter is
configured to operate in the first power mode while the first device and
the wireless charging device form a tightly coupled system.

3. The device of claim 1, wherein the at least one transmitter is
configured to operate in the second, reduced power mode while one or more
other devices and the wireless charging device form a loosely coupled
system.

4. The device of claim 1, wherein the at least one transmitter is
configured to detect a loading effect of one or more receive antennas
positioned within an associated charging region.

5. The device of claim 4, wherein the at least one transmitter is
configured to determine if either a loosely coupled system exists with
the one or more receive antennas or a tightly coupled system exists with
the one or more receive antennas based on at least one of the detected
loading effect, communication means, and an alignment device.

6. The device of claim 1, wherein the first device comprises a receive
antenna having a dimension substantially similar to a dimension of the
transmit antenna.

7. The device of claim 1, further comprising an alignment device
configured to enable substantial alignment of a receive antenna of the
first device with the transmit antenna of the at least one transmitter.

8. The device of claim 1, wherein the one or more other devices comprise
at least one of a cellular telephone, a portable media player, a camera,
a gaming device, a navigation device, and a headset.

9. The device of claim 1, further comprising a charging surface configured
for placement of the first device and the one or more other devices.

10. The device of claim 9, wherein the transmit antenna is positioned
proximate the charging surface.

11. The device of claim 1, wherein the wireless charging device comprises
at least one of a docking station, a charging tray, and a charging pad.

12. A method, comprising:conveying wireless power to a device at a first
power level during a time period; andconveying wireless power to one or
more other devices at a second, different power level during another time
period.

13. The method of claim 12, wherein conveying wireless power to the device
comprises conveying wireless power to a laptop computer.

14. The method of claim 12, wherein conveying wireless power to the one or
more other devices comprises conveying wireless power to at least one of
a cellular telephone, a portable media player, a camera, a gaming device,
a navigation device, and a headset.

15. The method of claim 12, further comprising determining that the device
and a wireless charging device comprise a tightly coupled system prior to
conveying wireless power to the device at the first power level.

16. The method of claim 12, wherein determining that the device and a
wireless charging device comprise a tightly coupled system comprises at
least one of detecting a loading effect on the wireless charging device,
communicating between the device and the wireless charging device, and
sensing the device with an alignment device of the wireless charging
device.

17. The method of claim 12, further comprising determining that the one or
more other devices and a wireless charging device comprise a loosely
coupled system prior to conveying wireless power to the one or more other
devices at a second, different power level.

18. The method of claim 12, wherein determining that the one or more other
devices and a wireless charging device comprise a loosely coupled system
comprises at least one of detecting a loading effect between the one or
more other devices and a wireless charging device and exchanging data
between the one or more other devices and the wireless charging device.

19. The method of claim 12, further comprising substantially aligning a
receive antenna of the device with a transmit antenna of a wireless
charging device prior to conveying wireless power to the device at the
first power level.

20. The method of claim 19, wherein substantially aligning comprises
substantially aligning the receive antenna of the device with the
transmit antenna of the wireless charging device with at least one
alignment mechanism coupled to the wireless charging device.

21. The method of claim 12, wherein conveying wireless power to the one or
more other devices at the second, different power level comprises
conveying wireless power to the one or more other devices at a power
level less than the first power level.

22. A device, comprising:means for conveying wireless power to a first
device at a first power level during a time period; andmeans for
conveying wireless power to one or more second devices at a second,
different power level during another time period.

Description:

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

[0001]This application claims priority under 35 U.S.C. §119(e) to:

[0002]U.S. Provisional Patent Application No. 61/241,344 entitled "DOCKING
TRAY WITH DUAL CHARGING MODE" filed on Sep. 10, 2009, the disclosure of
which is hereby incorporated by reference in its entirety.

BACKGROUND

[0003]1. Field

[0004]The present invention relates generally to wireless power, and more
specifically, to a wireless power charging device configured to operate
in various charging modes.

[0005]2. Background

[0006]Typically, each battery powered device requires its own charger and
power source, which is usually an AC power outlet. This becomes unwieldy
when many devices need charging.

[0007]Approaches are being developed that use over the air power
transmission between a transmitter and the device to be charged. These
generally fall into two categories. One is based on the coupling of plane
wave radiation (also called far-field radiation) between a transmit
antenna and receive antenna on the device to be charged which collects
the radiated power and rectifies it for charging the battery. Antennas
are generally of resonant length in order to improve the coupling
efficiency. This approach suffers from the fact that the power coupling
falls off quickly with distance between the antennas. So charging over
reasonable distances (e.g., >1-2 m) becomes difficult. Additionally,
since the system radiates plane waves, unintentional radiation can
interfere with other systems if not properly controlled through
filtering.

[0008]Other approaches are based on inductive coupling between a transmit
antenna embedded, for example, in a "charging" mat or surface and a
receive antenna plus rectifying circuit embedded in the host device to be
charged. This approach has the disadvantage that the spacing between
transmit and receive antennas must be very close (e.g. mms). Though this
approach does have the capability to simultaneously charge multiple
devices in the same area, this area is typically small, hence the user
must locate the devices to a specific area.

[0009]As will be understood by a person having ordinary skill in the art,
due to loose coupling, a wireless charger may not be able to provide
enough current to a battery of a portable computing device, such as a
NetBook, to charge the battery in a reasonable time. Furthermore,
providing a sufficient charge may require a very high field in a loosely
coupled system, which may not satisfy Specific Absorption Rate (SAR)
requirements.

[0010]A need exists for a wireless charging device configured to
wirelessly provide power in a first mode for a loosely coupled system and
a second, different mode for a tightly coupled system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 shows a simplified block diagram of a wireless power transfer
system.

[0012]FIG. 2 shows a simplified schematic diagram of a wireless power
transfer system.

[0013]FIG. 3 illustrates a schematic diagram of a loop antenna for use in
exemplary embodiments of the present invention.

[0014]FIG. 4 is a simplified block diagram of a transmitter, in accordance
with an exemplary embodiment of the present invention.

[0015]FIG. 5 is a simplified block diagram of a receiver, in accordance
with an exemplary embodiment of the present invention.

[0016]FIG. 6 shows a simplified schematic of a portion of transmit
circuitry for carrying out messaging between a transmitter and a
receiver.

[0017]FIG. 7 illustrates proximity coupling of a transmitter and a
receiver in a wireless power transmission system, in accordance with an
exemplary embodiment of the present invention.

[0018]FIG. 8 illustrates vicinity coupling of a transmitter and a receiver
in a wireless power transmission system, in accordance with an exemplary
embodiment.

[0019]FIG. 9 is a block diagram of a wireless charging device, in
accordance with an exemplary embodiment of the present invention.

[0020]FIG. 10 is an illustration of a wireless charging device having at
least one transmit antenna, according to an exemplary embodiment of the
present invention.

[0021]FIG. 11 is an illustration of a chargeable device being positioned
on a wireless charging device, in accordance with an exemplary embodiment
of the present invention.

[0022]FIG. 12 illustrates a plurality of chargeable devices positioned on
a wireless charging device, according to an exemplary embodiment of the
present invention.

[0023]FIG. 13 illustrates a plurality of chargeable devices positioned on
another chargeable device, which is positioned on a wireless charging
device, according to an exemplary embodiment of the present invention.

[0024]FIG. 14 is a flowchart illustrating a method, in accordance with an
exemplary embodiment of the present invention.

DETAILED DESCRIPTION

[0025]The detailed description set forth below in connection with the
appended drawings is intended as a description of exemplary embodiments
of the present invention and is not intended to represent the only
embodiments in which the present invention can be practiced. The term
"exemplary" used throughout this description means "serving as an
example, instance, or illustration," and should not necessarily be
construed as preferred or advantageous over other exemplary embodiments.
The detailed description includes specific details for the purpose of
providing a thorough understanding of the exemplary embodiments of the
invention. It will be apparent to those skilled in the art that the
exemplary embodiments of the invention may be practiced without these
specific details. In some instances, well-known structures and devices
are shown in block diagram form in order to avoid obscuring the novelty
of the exemplary embodiments presented herein.

[0026]The words "wireless power" is used herein to mean any form of energy
associated with electric fields, magnetic fields, electromagnetic fields,
or otherwise that is transmitted between a transmitter to a receiver
without the use of physical electrical conductors.

[0027]FIG. 1 illustrates a wireless transmission or charging system 100,
in accordance with various exemplary embodiments of the present
invention. Input power 102 is provided to a transmitter 104 for
generating a radiated field 106 for providing energy transfer. A receiver
108 couples to the radiated field 106 and generates an output power 110
for storing or consumption by a device (not shown) coupled to the output
power 110. Both the transmitter 104 and the receiver 108 are separated by
a distance 112. In one exemplary embodiment, transmitter 104 and receiver
108 are configured according to a mutual resonant relationship and when
the resonant frequency of receiver 108 and the resonant frequency of
transmitter 104 are very close, transmission losses between the
transmitter 104 and the receiver 108 are minimal when the receiver 108 is
located in the "near-field" of the radiated field 106.

[0028]Transmitter 104 further includes a transmit antenna 114 for
providing a means for energy transmission and receiver 108 further
includes a receive antenna 118 for providing a means for energy
reception. The transmit and receive antennas are sized according to
applications and devices to be associated therewith. As stated, an
efficient energy transfer occurs by coupling a large portion of the
energy in the near-field of the transmitting antenna to a receiving
antenna rather than propagating most of the energy in an electromagnetic
wave to the far field. When in this near-field a coupling mode may be
developed between the transmit antenna 114 and the receive antenna 118.
The area around the antennas 114 and 118 where this near-field coupling
may occur is referred to herein as a coupling-mode region.

[0029]FIG. 2 shows a simplified schematic diagram of a wireless power
transfer system. The transmitter 104 includes an oscillator 122, a power
amplifier 124 and a filter and matching circuit 126. The oscillator is
configured to generate a signal at a desired frequency, which may be
adjusted in response to adjustment signal 123. The oscillator signal may
be amplified by the power amplifier 124 with an amplification amount
responsive to control signal 125. The filter and matching circuit 126 may
be included to filter out harmonics or other unwanted frequencies and
match the impedance of the transmitter 104 to the transmit antenna 114.

[0030]The receiver 108 may include a matching circuit 132 and a rectifier
and switching circuit 134 to generate a DC power output to charge a
battery 136 as shown in FIG. 2 or power a device coupled to the receiver
(not shown). The matching circuit 132 may be included to match the
impedance of the receiver 108 to the receive antenna 118. The receiver
108 and transmitter 104 may communicate on a separate communication
channel 119 (e.g., Bluetooth, zigbee, cellular, etc).

[0031]As illustrated in FIG. 3, antennas used in exemplary embodiments may
be configured as a "loop" antenna 150, which may also be referred to
herein as a "magnetic" antenna. Loop antennas may be configured to
include an air core or a physical core such as a ferrite core. Air core
loop antennas may be more tolerable to extraneous physical devices placed
in the vicinity of the core. Furthermore, an air core loop antenna allows
the placement of other components within the core area. In addition, an
air core loop may more readily enable placement of the receive antenna
118 (FIG. 2) within a plane of the transmit antenna 114 (FIG. 2) where
the coupled-mode region of the transmit antenna 114 (FIG. 2) may be more
powerful.

[0032]As stated, efficient transfer of energy between the transmitter 104
and receiver 108 occurs during matched or nearly matched resonance
between the transmitter 104 and the receiver 108. However, even when
resonance between the transmitter 104 and receiver 108 are not matched,
energy may be transferred, although the efficiency may be affected.
Transfer of energy occurs by coupling energy from the near-field of the
transmitting antenna to the receiving antenna residing in the
neighborhood where this near-field is established rather than propagating
the energy from the transmitting antenna into free space.

[0033]The resonant frequency of the loop or magnetic antennas is based on
the inductance and capacitance. Inductance in a loop antenna is generally
simply the inductance created by the loop, whereas, capacitance is
generally added to the loop antenna's inductance to create a resonant
structure at a desired resonant frequency. As a non-limiting example,
capacitor 152 and capacitor 154 may be added to the antenna to create a
resonant circuit that generates resonant signal 156. Accordingly, for
larger diameter loop antennas, the size of capacitance needed to induce
resonance decreases as the diameter or inductance of the loop increases.
Furthermore, as the diameter of the loop or magnetic antenna increases,
the efficient energy transfer area of the near-field increases. Of
course, other resonant circuits are possible. As another non-limiting
example, a capacitor may be placed in parallel between the two terminals
of the loop antenna. In addition, those of ordinary skill in the art will
recognize that for transmit antennas the resonant signal 156 may be an
input to the loop antenna 150.

[0034]FIG. 4 is a simplified block diagram of a transmitter 200, in
accordance with an exemplary embodiment of the present invention. The
transmitter 200 includes transmit circuitry 202 and a transmit antenna
204. Generally, transmit circuitry 202 provides RF power to the transmit
antenna 204 by providing an oscillating signal resulting in generation of
near-field energy about the transmit antenna 204. It is noted that
transmitter 200 may operate at any suitable frequency. By way of example,
transmitter 200 may operate at the 13.56 MHz ISM band.

[0035]Exemplary transmit circuitry 202 includes a fixed impedance matching
circuit 206 for matching the impedance of the transmit circuitry 202
(e.g., 50 ohms) to the transmit antenna 204 and a low pass filter (LPF)
208 configured to reduce harmonic emissions to levels to prevent
self-jamming of devices coupled to receivers 108 (FIG. 1). Other
exemplary embodiments may include different filter topologies, including
but not limited to, notch filters that attenuate specific frequencies
while passing others and may include an adaptive impedance match, that
can be varied based on measurable transmit metrics, such as output power
to the antenna or DC current drawn by the power amplifier. Transmit
circuitry 202 further includes a power amplifier 210 configured to drive
an RF signal as determined by an oscillator 212. The transmit circuitry
may be comprised of discrete devices or circuits, or alternately, may be
comprised of an integrated assembly. An exemplary RF power output from
transmit antenna 204 may be on the order of 2.5 Watts.

[0036]Transmit circuitry 202 further includes a controller 214 for
enabling the oscillator 212 during transmit phases (or duty cycles) for
specific receivers, for adjusting the frequency or phase of the
oscillator, and for adjusting the output power level for implementing a
communication protocol for interacting with neighboring devices through
their attached receivers.

[0037]The transmit circuitry 202 may further include a load sensing
circuit 216 for detecting the presence or absence of active receivers in
the vicinity of the near-field generated by transmit antenna 204. By way
of example, a load sensing circuit 216 monitors the current flowing to
the power amplifier 210, which is affected by the presence or absence of
active receivers in the vicinity of the near-field generated by transmit
antenna 204. Detection of changes to the loading on the power amplifier
210 are monitored by controller 214 for use in determining whether to
enable the oscillator 212 for transmitting energy and to communicate with
an active receiver.

[0038]Transmit antenna 204 may be implemented with a Litz wire or as an
antenna strip with the thickness, width and metal type selected to keep
resistive losses low. In a conventional implementation, the transmit
antenna 204 can generally be configured for association with a larger
structure such as a table, mat, lamp or other less portable
configuration. Accordingly, the transmit antenna 204 generally will not
need "turns" in order to be of a practical dimension. An exemplary
implementation of a transmit antenna 204 may be "electrically small"
(i.e., fraction of the wavelength) and tuned to resonate at lower usable
frequencies by using capacitors to define the resonant frequency. In an
exemplary application where the transmit antenna 204 may be larger in
diameter, or length of side if a square loop, (e.g., 0.50 meters)
relative to the receive antenna, the transmit antenna 204 will not
necessarily need a large number of turns to obtain a reasonable
capacitance.

[0039]The transmitter 200 may gather and track information about the
whereabouts and status of receiver devices that may be associated with
the transmitter 200. Thus, the transmitter circuitry 202 may include a
presence detector 280, an enclosed detector 290, or a combination
thereof, connected to the controller 214 (also referred to as a processor
herein). The controller 214 may adjust an amount of power delivered by
the amplifier 210 in response to presence signals from the presence
detector 280 and the enclosed detector 290. The transmitter may receive
power through a number of power sources, such as, for example, an AC-DC
converter (not shown) to convert conventional AC power present in a
building, a DC-DC converter (not shown) to convert a conventional DC
power source to a voltage suitable for the transmitter 200, or directly
from a conventional DC power source (not shown).

[0040]As a non-limiting example, the presence detector 280 may be a motion
detector utilized to sense the initial presence of a device to be charged
that is inserted into the coverage area of the transmitter. After
detection, the transmitter may be turned on and the RF power received by
the device may be used to toggle a switch on the Rx device in a
pre-determined manner, which in turn results in changes to the driving
point impedance of the transmitter.

[0041]As another non-limiting example, the presence detector 280 may be a
detector capable of detecting a human, for example, by infrared
detection, motion detection, or other suitable means. In some exemplary
embodiments, there may be regulations limiting the amount of power that a
transmit antenna may transmit at a specific frequency. In some cases,
these regulations are meant to protect humans from electromagnetic
radiation. However, there may be environments where transmit antennas are
placed in areas not occupied by humans, or occupied infrequently by
humans, such as, for example, garages, factory floors, shops, and the
like. If these environments are free from humans, it may be permissible
to increase the power output of the transmit antennas above the normal
power restrictions regulations. In other words, the controller 214 may
adjust the power output of the transmit antenna 204 to a regulatory level
or lower in response to human presence and adjust the power output of the
transmit antenna 204 to a level above the regulatory level when a human
is outside a regulatory distance from the electromagnetic field of the
transmit antenna 204.

[0042]As a non-limiting example, the enclosed detector 290 (may also be
referred to herein as an enclosed compartment detector or an enclosed
space detector) may be a device such as a sense switch for determining
when an enclosure is in a closed or open state. When a transmitter is in
an enclosure that is in an enclosed state, a power level of the
transmitter may be increased.

[0043]In exemplary embodiments, a method by which the transmitter 200 does
not remain on indefinitely may be used. In this case, the transmitter 200
may be programmed to shut off after a user-determined amount of time.
This feature prevents the transmitter 200, notably the power amplifier
210, from running long after the wireless devices in its perimeter are
fully charged. This event may be due to the failure of the circuit to
detect the signal sent from either the repeater or the receive coil that
a device is fully charged. To prevent the transmitter 200 from
automatically shutting down if another device is placed in its perimeter,
the transmitter 200 automatic shut off feature may be activated only
after a set period of lack of motion detected in its perimeter. The user
may be able to determine the inactivity time interval, and change it as
desired. As a non-limiting example, the time interval may be longer than
that needed to fully charge a specific type of wireless device under the
assumption of the device being initially fully discharged.

[0044]FIG. 5 is a simplified block diagram of a receiver 300, in
accordance with an exemplary embodiment of the present invention. The
receiver 300 includes receive circuitry 302 and a receive antenna 304.
Receiver 300 further couples to device 350 for providing received power
thereto. It should be noted that receiver 300 is illustrated as being
external to device 350 but may be integrated into device 350. Generally,
energy is propagated wirelessly to receive antenna 304 and then coupled
through receive circuitry 302 to device 350.

[0045]Receive antenna 304 is tuned to resonate at the same frequency, or
within a specified range of frequencies, as transmit antenna 204 (FIG.
4). Receive antenna 304 may be similarly dimensioned with transmit
antenna 204 or may be differently sized based upon the dimensions of the
associated device 350. By way of example, device 350 may be a portable
electronic device having diametric or length dimension smaller that the
diameter of length of transmit antenna 204. In such an example, receive
antenna 304 may be implemented as a multi-turn antenna in order to reduce
the capacitance value of a tuning capacitor (not shown) and increase the
receive antenna's impedance. By way of example, receive antenna 304 may
be placed around the substantial circumference of device 350 in order to
maximize the antenna diameter and reduce the number of loop turns (i.e.,
windings) of the receive antenna and the inter-winding capacitance.

[0046]Receive circuitry 302 provides an impedance match to the receive
antenna 304. Receive circuitry 302 includes power conversion circuitry
306 for converting a received RF energy source into charging power for
use by device 350. Power conversion circuitry 306 includes an RF-to-DC
converter 308 and may also in include a DC-to-DC converter 310. RF-to-DC
converter 308 rectifies the RF energy signal received at receive antenna
304 into a non-alternating power while DC-to-DC converter 310 converts
the rectified RF energy signal into an energy potential (e.g., voltage)
that is compatible with device 350. Various RF-to-DC converters are
contemplated, including partial and full rectifiers, regulators, bridges,
doublers, as well as linear and switching converters.

[0047]Receive circuitry 302 may further include switching circuitry 312
for connecting receive antenna 304 to the power conversion circuitry 306
or alternatively for disconnecting the power conversion circuitry 306.
Disconnecting receive antenna 304 from power conversion circuitry 306 not
only suspends charging of device 350, but also changes the "load" as
"seen" by the transmitter 200 (FIG. 2).

[0048]As disclosed above, transmitter 200 includes load sensing circuit
216 which detects fluctuations in the bias current provided to
transmitter power amplifier 210. Accordingly, transmitter 200 has a
mechanism for determining when receivers are present in the transmitter's
near-field.

[0049]When multiple receivers 300 are present in a transmitter's
near-field, it may be desirable to time-multiplex the loading and
unloading of one or more receivers to enable other receivers to more
efficiently couple to the transmitter. A receiver may also be cloaked in
order to eliminate coupling to other nearby receivers or to reduce
loading on nearby transmitters. This "unloading" of a receiver is also
known herein as a "cloaking." Furthermore, this switching between
unloading and loading controlled by receiver 300 and detected by
transmitter 200 provides a communication mechanism from receiver 300 to
transmitter 200 as is explained more fully below. Additionally, a
protocol can be associated with the switching which enables the sending
of a message from receiver 300 to transmitter 200. By way of example, a
switching speed may be on the order of 100 μsec.

[0050]In an exemplary embodiment, communication between the transmitter
and the receiver refers to a device sensing and charging control
mechanism, rather than conventional two-way communication. In other
words, the transmitter may use on/off keying of the transmitted signal to
adjust whether energy is available in the near-filed. The receivers
interpret these changes in energy as a message from the transmitter. From
the receiver side, the receiver may use tuning and de-tuning of the
receive antenna to adjust how much power is being accepted from the
near-field. The transmitter can detect this difference in power used from
the near-field and interpret these changes as a message from the
receiver. It is noted that other forms of modulation of the transmit
power and the load behavior may be utilized.

[0051]Receive circuitry 302 may further include signaling detector and
beacon circuitry 314 used to identify received energy fluctuations, which
may correspond to informational signaling from the transmitter to the
receiver. Furthermore, signaling and beacon circuitry 314 may also be
used to detect the transmission of a reduced RF signal energy (i.e., a
beacon signal) and to rectify the reduced RF signal energy into a nominal
power for awakening either un-powered or power-depleted circuits within
receive circuitry 302 in order to configure receive circuitry 302 for
wireless charging.

[0052]Receive circuitry 302 further includes processor 316 for
coordinating the processes of receiver 300 described herein including the
control of switching circuitry 312 described herein. Cloaking of receiver
300 may also occur upon the occurrence of other events including
detection of an external wired charging source (e.g., wall/USB power)
providing charging power to device 350. Processor 316, in addition to
controlling the cloaking of the receiver, may also monitor beacon
circuitry 314 to determine a beacon state and extract messages sent from
the transmitter. Processor 316 may also adjust DC-to-DC converter 310 for
improved performance.

[0053]FIG. 6 shows a simplified schematic of a portion of transmit
circuitry for carrying out messaging between a transmitter and a
receiver. In some exemplary embodiments of the present invention, a means
for communication may be enabled between the transmitter and the
receiver. In FIG. 6 a power amplifier 210 drives the transmit antenna 204
to generate the radiated field. The power amplifier is driven by a
carrier signal 220 that is oscillating at a desired frequency for the
transmit antenna 204. A transmit modulation signal 224 is used to control
the output of the power amplifier 210.

[0054]The transmit circuitry can send signals to receivers by using an
ON/OFF keying process on the power amplifier 210. In other words, when
the transmit modulation signal 224 is asserted, the power amplifier 210
will drive the frequency of the carrier signal 220 out on the transmit
antenna 204. When the transmit modulation signal 224 is negated, the
power amplifier will not drive out any frequency on the transmit antenna
204. It is noted that other types of modulation may be within the scope
of the present invention.

[0055]The transmit circuitry of FIG. 6 also includes a load sensing
circuit 216 that supplies power to the power amplifier 210 and generates
a receive signal 235 output. In the load sensing circuit 216 a voltage
drop across resistor Rs develops between the power in signal 226 and
the power supply 228 to the power amplifier 210. Any change in the
current consumed by the power amplifier 210 will cause a change in the
voltage drop that will be amplified by differential amplifier 230. When
the transmit antenna is in coupled mode with a receive antenna in a
receiver (not shown in FIG. 6) the amount of current drawn by the power
amplifier 210 will change. In other words, if no coupled mode resonance
exist for the transmit antenna 204, the power required to drive the
radiated field will be a first amount. If a coupled mode resonance
exists, the amount of power consumed by the power amplifier 210 will go
up because much of the power is being coupled into the receive antenna.
Thus, the receive signal 235 can indicate the presence of a receive
antenna coupled to the transmit antenna 235 and can also detect signals
sent from the receive antenna. Additionally, a change in receiver current
draw will be observable in the transmitter's power amplifier current
draw, and this change can be used to detect signals from the receive
antennas. It is noted that other circuit may be implemented to detect
variation in the load presented by the behavior of the receive antenna
and associated circuitry

[0056]Various exemplary embodiments disclosed herein identify different
coupling variants which are based on different power conversion
approaches, and the transmission range including device positioning
flexibility (e.g., close "proximity" coupling for charging pad solutions
at virtually zero distance or "vicinity" coupling for short range
wireless power solutions). Close proximity coupling applications (i.e.,
strongly coupled regime, coupling factor typically k >0.1) provide
energy transfer over short or very short distances typically in the order
of millimeters or centimeters depending on the size of the antennas.
Vicinity coupling applications (i.e., loosely coupled regime, coupling
factor typically k <0.1) provide energy transfer at relatively lower
efficiency over distances typically in the range from 10 cm to 2 m
depending on the size of the antennas. While "vicinity" coupling between
a transmitter and receiver may provide lower efficiency energy transfer,
"vicinity" coupling provides flexibility in positioning of the receiver
(with the device attached thereto) with respect to the transmitter
antenna.

[0057]As described herein, "proximity" coupling and "vicinity" coupling
may require different matching approaches to adapt power source/sink to
the antenna/coupling network. Moreover, the various exemplary embodiments
provide system parameters, design targets, implementation variants, and
specifications for both LF and HF applications and for the transmitter
and receiver. Some of these parameters and specifications may vary, as
required for example, to better match with a specific power conversion
approach

[0058]FIG. 7 illustrates a functional block diagram of a first coupling
variant between transmit and receive antennas, in accordance with an
exemplary embodiment. The coupling variant 350 of FIG. 7 illustrates a
"vicinity" coupling variant and may be used to couple to a high-Q
resonant tank circuit used for "vicinity" coupling. Coupling variant 350
transforms impedances to match with power conversion circuitry resulting
in an improved or high transfer efficiency. Specifically, coupling
variant 350 includes a transmit antenna 352 configured to resonate and a
resonant frequency and a receive antenna 354 configured to resonate at
the same resonant frequency or at a frequency that is within a specified
range of the resonant frequency.

[0060]FIG. 8 illustrates a functional block diagram of a second coupling
variant between transmit and receive antennas, in accordance with an
exemplary embodiment. The coupling variant 380 of FIG. 8 illustrates a
"proximity" coupling variant, in accordance with an exemplary embodiment.
Coupling variant 380 includes the transmit antenna 352 and the receive
antenna 354 of FIG. 7. The transmit antenna 352 includes the high-Q tank
resonator 356, including capacitor C1 and inductor L1, and the
receive antenna 354 includes the high-Q tank resonator 358, including
capacitor C2 and inductor L2. Close proximity coupling
applications (i.e., strongly coupled regime with a coupling factor
typically k >0.1) provide energy transfer over short or very short
distances d typically in the order of millimeters or centimeters,
depending on the size of the antennas.

[0061]Generally, wireless power transfer according to resonant induction
is improved by determining an optimum load resistance resulting in
maximized transfer efficiency for given antenna parameters (e.g.,
unloaded Q-factors, L-C ratios, and transmitter source impedance). The
optimum loading depends on coupling factor k. Conversely, there exists an
optimum receive L-C ratio or load transformation maximizing efficiency
for a given load resistance.

[0062]Exemplary embodiments of the invention are related to a wireless
charging device configured to operate in one of a plurality of charging
modes while maintaining compatibility with FCC/SAR regulations. The
wireless charging device may be configured to provide power to a large
load (e.g., a laptop computer) in a tightly coupled system or provide
power to one or more smaller loads (e.g., mobile telephones or media
players) in a loosely coupled system.

[0063]The wireless charging device may include at least one wireless power
transmitter configured to transmitting wireless power within an
associated near-field region. According to one exemplary embodiment, the
at least one wireless power transmitter may be configured to vary,
depending on a type of one or more chargeable devices positioned within
an associated charging region, an amount of power wirelessly transmitted
therefrom. More specifically, the wireless power transmitter may be
configured for dedicated (i.e., 1 to 1) high-power charging for a high
capacity battery, such as a battery of a laptop computer (e.g., a Netbook
or a Smartbook). Stated another way, the wireless power transmitter may
be configured to transmit a relatively high level of power to a single
device, which forms a tightly coupled system (i.e., proximity coupling)
with the wireless charging device. Furthermore, the wireless power
transmitter may be configured for low-power charging for one or more
(e.g., 1 to many) low capacity batteries, such as a battery of a mobile
telephone or a media player. Stated another way, the wireless charging
device may be configured to transmit a relatively low level of power to
one or more devices, which form a loosely coupled system (i.e., vicinity
coupling) with the wireless charging device.

[0064]As will be appreciated by a person having ordinary skill in the art,
chargeable batteries of relatively low power devices, such as, for
example only, a cellular telephone or a portable media player, may
require approximately 2 to 3 watts of power for adequate charging. On the
other hand, chargeable batteries of relatively high power devices, such
as a laptop computer, may require approximately 60 watts of power for
adequate charging. Accordingly, wirelessly transmitting an adequate
amount of power to a relatively high power device in a loosely coupled
system may result in greater power loss than transmitting an adequate
amount of power to one or more small devices in a loosely coupled system.
Furthermore, although a loosely coupled system may exhibit a higher
percentage of loss compared to a tightly coupled system, if the amount of
power transmitted in a loosely coupled system is relatively low (e.g., 2
to 3 watts), the amount of power lost may also be relatively low.
Conversely, if the amount of power transmitted in a loosely coupled
system is relatively high (e.g., 60 watts) the amount of power lost may
also be relatively high.

[0065]FIG. 9 is a block diagram of a wireless charging device 700
including a transmitter (e.g., transmitter 200 of FIG. 4) and at least
one associated transmit antenna 702. For example only, wireless charging
device 700 may comprise a charging tray, a charging pad, a docking
station, or any combination thereof. It is noted that the term "high
power device," as used herein comprises a device that requires a
relatively high amount of power (e.g., 60 watts) to be charged in
comparison to a low power device, such as, for example only, a cellular
telephone, a Bluetooth headset, or a portable media player, which may
require, for example only, 2 to 3 watts of power to be charged. Moreover,
a high power device may comprise a receive antenna having dimensions that
are substantially similar to the dimensions of transmit antenna 702 of a
wireless charging device 700. Furthermore, as used herein the term "low
power device" (e.g., a device that requires low power to be charged
(e.g., 2 to 3 watts) relative to a high power device) may comprise a
device having a receive antenna with dimensions that are substantially
smaller than the dimensions of transmit antenna 702 of a wireless
charging device 700.

[0066]As described more fully below, depending on a type of one or more
chargeable devices positioned within an associated charging region of
wireless charging device 700, wireless charging device 700 may be
configured to adjust an amount of power transmitted therefrom. More
specifically, wireless charging device 700 may be configured to transmit
power at a power level in a tightly coupled system (i.e., proximity
coupling) and transmit power at another, lesser power level in a loosely
coupled system (i.e., vicinity coupling). Stated another way, if one or
more relatively low power devices (e.g., one or more mobile telephones)
are positioned within a charging region of wireless charging device 700
(e.g., on a surface of wireless charging device 700), wireless charging
device 700 may be configured to transmit a relatively small amount of
power (e.g., 2-3 watts per device actively receiving power). Conversely,
if a large device (e.g., a laptop) is positioned within a charging region
of wireless charging device 700, wireless charging device 700 may be
configured to transmit an amount of power (e.g., 60 watts), which is
relatively high compared to the amount of power transmitted while one or
more small devices are positioned within the charging region. Such change
in the amount of power may be actively controlled by 700 or may be
automatically obtained by the characteristic impedance that one or more
chargeable device presents to wireless charging device 700.

[0067]FIG. 10 is another illustration of wireless charging device 700. As
illustrated in FIG. 10, wireless charging device 700 includes a surface
704 for placement of a large chargeable device (e.g., a laptop) or one or
more small chargeable devices (e.g., a cellular telephone, a media
player, or a camera).

[0068]As described more fully below, according to an exemplary embodiment
of the present invention, wireless charging device 700 may be configured
to perform a loading analysis to determine what type or types of
chargeable devices are positioned within an associated near-field region.
Stated another way, wireless charging device 700 may be configured to
analyze a loading effect of receive antennas positioned within an
associated near field region on the associated transmitter (i.e., whether
a relatively large load exists or a relatively small load exists). The
loading analysis may enable wireless charging device 700 to determine
whether a tightly coupled system is formed with one relatively large
device positioned within an associated near-field region or whether a
loosely coupled system is formed having one or more relatively small
devices positioned within an associated near-field region. According to
another exemplary embodiment, a chargeable device, which is positioned
within a near-field region of wireless charging device 700, may
communicate its presence and its "type" (i.e., whether it is a relatively
high power (e.g., a laptop) forming a tightly coupled system or whether
it is a relatively low power device (e.g., a mobile telephone) forming a
loosely coupled system) to wireless charging device 700.

[0069]Furthermore, in response to determining that a relatively high power
device is present and a tightly coupled system is formed, wireless
charging device 700 may allow for transmission of an appropriate amount
of power (e.g., 60 watts) to charge the relatively high power device.
Similarly, in response to determining that one or more relatively low
power devices are present and a loosely coupled system is formed,
wireless charging device 700 may transmit an adequate amount of power
(e.g., 2-3 watts) to charge the one or more relatively low power devices.
Moreover, it is noted that wireless charging device 700 may modify how an
associated transmit antenna is driven to optimize power transmission from
the associated transmit antenna to one or more devices positioned within
an associated charging region.

[0070]FIG. 11 depicts a device 910, which may comprise, for example, a
laptop computer, being positioned on wireless charging device 700. Device
910 may include a receiver (not shown in FIG. 11, see e.g., receiver 300
of FIG. 5) and at least one associated receive antenna (also not shown in
FIG. 11; see e.g., receive antenna 304 of FIG. 5). As noted above, a
relatively high power device (e.g., a laptop computer such as device 910)
may require a relatively large amount of power (e.g., 60 watts) for a
sufficient charge. Accordingly, device 910 should be positioned adjacent
wireless charging device 700 to enable a receive antenna of device 910 to
be positioned adjacent to transmit antenna 702 and, as a result, a
tightly coupled system may exist.

[0071]Accordingly to one exemplary embodiment, wireless charging device
700 may be configured to enable an associated transmit antenna 702 to
substantially align with a receive antenna of a relatively high power
device, such as a laptop computer. As will be appreciated by a person
having ordinary skill in the art, substantially aligning transmit antenna
702 with a receive antenna of a relatively high power device may provide
for a tightly coupled system (i.e., proximity coupling). For example
only, wireless charging device 700 may include one or more alignment
devices (e.g., one or more grooves, one or more brackets, or any
combination thereof), configured to assist a device user to substantially
align transmit antenna 702 with a receive antenna of a specific,
relatively high power device. More specifically, as one example, wireless
charging device 700 may include one or more alignment devices 913
configured for positioning device 910 on surface 704 to substantially
align transmit antenna 702 with a receive antenna of device 910. As
another example, wireless charging device 700 may comprise a docking
station configured for substantially aligning transmit antenna 702 with a
receive antenna of a relatively high power device positioned within a
near-field region of wireless charging device 700. It is noted that
wireless charging device 700 may include one or more alignment devices, a
device to be charged (e.g., device 910) may include one or more alignment
devices, or both wireless charging device 700 and device 910 may include
one or more alignment devices to enable respective antennas to be
substantially aligned, and, as a result, provide a tightly coupled
system.

[0072]It is noted that an alignment device (e.g., alignment device 913) or
a docking station may be configured to detect a relatively high power
device positioned within a near-field region of wireless charging device
700. For example only, alignment device 913 or a docking station may
include one or more sensors to detect a relatively high power device
positioned within a near-field region of wireless charging device 700.
Accordingly, wireless charging device 700 may be configured to detect a
tightly coupled system. It is further noted that after wireless charging
device 700 determines that a tightly coupled system is formed with a
relatively high power device, wireless charging device 700 may transmit a
relatively large amount of power (e.g., 60 watts), which is sufficient to
charge the device 910.

[0073]It is further noted that wireless charging device 700 may be
specifically designed and manufactured for a specific device 910, or vice
versa. Accordingly, antennas within each of wireless charging device 700
and device 910 may be positioned so as to substantially align upon device
910 being positioned within a charging region of wireless charging device
700.

[0074]FIG. 12 illustrates a plurality of devices 920 positioned on surface
704 of wireless charging device 700. Each device 920 may include a
receiver (not shown in FIG. 12, see e.g., receiver 300 of FIG. 5) and at
least one associated receive antenna (also not shown in FIG. 12; see
e.g., receive antenna 304 of FIG. 5). By way of example only, device 920
may comprise a cellular telephone, a portable media player, a camera, a
gaming device, a navigation device, a headset (e.g., a Bluetooth
headset), or any combination thereof. As noted above, a relatively low
power device (e.g., a mobile telephone) may require a relatively small
amount of power (e.g., 2-3 watts) for a sufficient charge. As will be
appreciated by a person having ordinary skill in the art, loosely coupled
system may be formed with one or more devices 920, which may be placed
freely within a charging region of wireless charging device 700. After
wireless charging device 700 determines that a loosely coupled system is
formed with one or more relatively low power devices 920, wireless
charging device 700 may transmit a relatively small amount of power
(e.g., 2-3 watts), which is sufficient to charge the one or more devices
920.

[0075]FIG. 13 depicts device 910, which, as noted above, may comprise, for
example, a laptop computer, being positioned on wireless charging device
700. As noted above, device 910 may include a receiver (not shown in FIG.
11, see e.g., receiver 300 of FIG. 5). As also noted above, device 910
may be positioned on surface 704 (see FIG. 10) of wireless charging
device 700 to enable transmit antenna 702 to be substantially aligned
with a receive antenna of device 910 and, as a result a tightly coupled
system may exist between device 910 and wireless charging device 700.
After wireless charging device 700 determines that a tightly coupled
system is formed with a relatively high power device 910, wireless
charging device 700 may transmit a relatively large amount of power
(e.g., 60 watts), which is sufficient to charge the device 910.

[0076]Furthermore, FIG. 13 also illustrates a plurality of devices 920
positioned on surface 915 of device 910. As noted above with respect to
FIG. 12, each device 920 may include a receiver (not shown in FIG. 12;
see e.g., receiver 300 of FIG. 5) and at least one associated receive
antenna (also not shown in FIG. 12; see e.g., receive antenna 304 of FIG.
5). According to one exemplary embodiment, antenna 950 may comprise a
repeater antenna. As will be understood by a person having ordinary skill
in the art, in an exemplary embodiment wherein antenna 950 comprises a
repeater antenna, antenna 950 may be configured to act as a relay for
power wirelessly transmitted from transmit antenna 702. Therefore, in
accordance with one exemplary embodiment, wireless power, which is
transmitted from wireless charging device 700 to device 910 in a tightly
coupled system may be repeated (i.e., re-transmitted) from device 910 to
devices 920 in a loosely coupled system.

[0077]According to another embodiment, device 910 may include a receive
antenna (e.g., receive antenna 300 of FIG. 5) and antenna 950, which is
configured to wirelessly transmit power from device 910 to one or more
chargeable devices (e.g., devices 920) positioned within an associated
near-field. Therefore, in accordance with one exemplary embodiment,
device 910 may wirelessly transmit power to one or more devices 920 in a
loosely coupled system. After wireless charging device 700 determines
that a loosely coupled system is formed with one or more relatively low
power devices 920, wireless charging device 700 may transmit a relatively
small amount of power (e.g., 2-3 watts per device 920), which is
sufficient to charge the one or more devices 920. It is noted antenna 300
of device 910 may be configured to operate as a repeater antenna, a
receive antenna, or both.

[0078]FIG. 14 is a flowchart illustrating a method 980, in accordance with
one or more exemplary embodiments. Method 980 may include conveying
wireless power to a device at a first power level during a time period
(depicted by numeral 982). Method 980 may further include conveying
wireless power to one or more other devices at a second, different power
level during another time period (depicted by numeral 984).

[0079]Those of skill in the art would understand that information and
signals may be represented using any of a variety of different
technologies and techniques. For example, data, instructions, commands,
information, signals, bits, symbols, and chips that may be referenced
throughout the above description may be represented by voltages,
currents, electromagnetic waves, magnetic fields or particles, optical
fields or particles, or any combination thereof.

[0080]Those of skill would further appreciate that the various
illustrative logical blocks, modules, circuits, and algorithm steps
described in connection with the exemplary embodiments disclosed herein
may be implemented as electronic hardware, computer software, or
combinations of both. To clearly illustrate this interchangeability of
hardware and software, various illustrative components, blocks, modules,
circuits, and steps have been described above generally in terms of their
functionality. Whether such functionality is implemented as hardware or
software depends upon the particular application and design constraints
imposed on the overall system. Skilled artisans may implement the
described functionality in varying ways for each particular application,
but such implementation decisions should not be interpreted as causing a
departure from the scope of the exemplary embodiments of the invention.

[0081]The various illustrative logical blocks, modules, and circuits
described in connection with the exemplary embodiments disclosed herein
may be implemented or performed with a general purpose processor, a
Digital Signal Processor (DSP), an Application Specific Integrated
Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other
programmable logic device, discrete gate or transistor logic, discrete
hardware components, or any combination thereof designed to perform the
functions described herein. A general purpose processor may be a
microprocessor, but in the alternative, the processor may be any
conventional processor, controller, microcontroller, or state machine. A
processor may also be implemented as a combination of computing devices,
e.g., a combination of a DSP and a microprocessor, a plurality of
microprocessors, one or more microprocessors in conjunction with a DSP
core, or any other such configuration.

[0082]The steps of a method or algorithm described in connection with the
exemplary embodiments disclosed herein may be embodied directly in
hardware, in a software module executed by a processor, or in a
combination of the two. A software module may reside in Random Access
Memory (RAM), flash memory, Read Only Memory (ROM), Electrically
Programmable ROM (EPROM), Electrically Erasable Programmable ROM
(EEPROM), registers, hard disk, a removable disk, a CD-ROM, or any other
form of storage medium known in the art. An exemplary storage medium is
coupled to the processor such that the processor can read information
from, and write information to, the storage medium. In the alternative,
the storage medium may be integral to the processor. The processor and
the storage medium may reside in an ASIC. The ASIC may reside in a user
terminal. In the alternative, the processor and the storage medium may
reside as discrete components in a user terminal.

[0083]In one or more exemplary embodiments, the functions described may be
implemented in hardware, software, firmware, or any combination thereof.
If implemented in software, the functions may be stored on or transmitted
over as one or more instructions or code on a computer-readable medium.
Computer-readable media includes both computer storage media and
communication media including any medium that facilitates transfer of a
computer program from one place to another. A storage media may be any
available media that can be accessed by a computer. By way of example,
and not limitation, such computer-readable media can comprise RAM, ROM,
EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or
other magnetic storage devices, or any other medium that can be used to
carry or store desired program code in the form of instructions or data
structures and that can be accessed by a computer. Also, any connection
is properly termed a computer-readable medium. For example, if the
software is transmitted from a website, server, or other remote source
using a coaxial cable, fiber optic cable, twisted pair, digital
subscriber line (DSL), or wireless technologies such as infrared, radio,
and microwave, then the coaxial cable, fiber optic cable, twisted pair,
DSL, or wireless technologies such as infrared, radio, and microwave are
included in the definition of medium. Disk and disc, as used herein,
includes compact disc (CD), laser disc, optical disc, digital versatile
disc (DVD), floppy disk and blu-ray disc where disks usually reproduce
data magnetically, while discs reproduce data optically with lasers.
Combinations of the above should also be included within the scope of
computer-readable media.

[0084]The previous description of the disclosed exemplary embodiments is
provided to enable any person skilled in the art to make or use the
present invention. Various modifications to these exemplary embodiments
will be readily apparent to those skilled in the art, and the generic
principles defined herein may be applied to other embodiments without
departing from the spirit or scope of the invention. Thus, the present
invention is not intended to be limited to the exemplary embodiments
shown herein but is to be accorded the widest scope consistent with the
principles and novel features disclosed herein.